Process of making lead sucrate.



NlTED ra'rns FFICE,

cnoae KASSNER, or MUNSTER, GERMANY.

PROCESS OF MAKING LEAD SUCRATE.

SPECIFICATION forming part of Letters Patent No. 628,985, dated July 18,1899. Application filed August 21,1395. Serial No. 559,987. (Nospecimens.)

To all whom, it may concern.-

Be it known that I, GEORG KASSNER, professor, a subject of theGermanEmperor, and a resident of Munster, in the Province of WVestphalia andGerman Empire, have invented a certain new and useful Improved Processof Manufacture of Sugar, (patented in Great Britain, No.14,925, August7, 1895,) of which the following is a specification.

The best process that has been employed hitherto for extracting canesugar from sacchariferous solutions in the condition of a compounddissolving with difficulty is unquestionably that which consists inturning to account the property which is possessed by barium hydrate andstrontium hydrate of combining with cane sugar. This method of utilizingthe alkaline earths is, however, attended with three somewhat seriousdrawbacks, which reside in the very nature of the chemical agents named,and therefore may be neither obviated nor preventedviz., first, that thehydrate of strontium and barium hydrate will only separate cane sugarand raffinose and have a destructive action upon the various kinds ofglucose, so that the extraction and separation for m anufacturing orcommercial purposes of glucose on the one hand andof cane sugar on theother, as well as the extraction of the soluble salts contained in thejuices of plants, become impracticable; second, that the strontium orbarium sucrates are by far too readily soluble to admit of the foreignsalts and coloring agents being separated therefrom bylixiviation, and,third,that the process of regeneration of the alkaline earths from thecarbonates formed in the saturation stage requires too high temperaturesfor its performance, thereby adding Very considerable to the cost of thefuel consumed, while the furnaces which have to be used in carrying itout are liable to speedy destruction.

Now the process forming the subject of this invention is free from thedefects above enumerated. It involves the employment of OX- ide of leadas a separating agent and is based upon the fact (which is well known toscientists) that it yields combinations of sugar and lead which are onlysoluble with difliculty. This, as stated, was merely a scientificdiscovery, as was also the circumstance which was first pointed out byDubrunfaut-that sucrate of lead forms at ordinary temperature, and thatit does so gradually, when litharge is allowed to stand at rest togetherwith a pure solution of sugar. These scientific data,taken bythemselves, were of no practical value and totally unfit to render anyservice to the trade, lacking, as they did, various features essentialto success; and, in truth, it has hitherto occurred to no one to attemptto render Du brunfauts discovery serviceable for the trade or market,for extracting sugar from molasses or from any'mixture embodying foreignor impure substances, much less for separating the several kinds ofsugar from each other, all this having been impracticable for Want ofexperience and because the behavior of lead in the different casesalluded to was unknown. I therefore have assumed the task ofascertaining the requirements to be fulfilled, which, not having beenknown before, might not be complied with.

I have after numerous trials, partly unsuccessful, at length succeededin devising a really serviceable process, and, what is better still, inimparting to it the character of a continuous circular process, (or whatis sometimes called a cycle,) wherein all the materials or agentsemployed are brought back to their starting-points after havingperformed their respective duties.

The most important conditions upon which the successful performance ofthe process depends are as follows:

a. The oxide of lead employed should be in the form of a powder whichmust be as fine and as uniform as possible.

1). Between the oxide of lead and the sugar there should be apredetermined relation of weight, especially when the process is carriedon on rational ].inesthat is to say, for manufacturing or commercialpurposes.

0. The concentration of the solution should be so proportionedthat theresulting combination of oxide of lead with the sugar can be but slowlyprecipitated at the bottom of the vessel.

01. Care should be taken to insure as close and as uniform a contact aspossible between the heavy insoluble oxide of lead and the solution ofsugar. This may be done, for example, by keeping the mixture in violentmotion or briskly stirring it until sucrate begins to form.

6. The separation of the sucrates should be so conducted that thevarious sorts of sugar may be collected separately. This last-mentionedresult will be obtained by taking advantage of a fact which I have alsohad occasion to ascertain in the course of my labors namely, that wherea mixture of various species of sugar is dealt with the oxide of leadwill cause the glucose (levulose and dextrose) in its various forms tobe precipitated first, while the cane sugar will not precipitate untilafterward. The glucosate being precipitated first and the sucrateafterward, the former is removed mechanically before the precipitationof the latter. Attention should also be paid to the desideratum ofobtaining the sucrate in' the condition of agglomerated lumps having theshape of small balls or warts and consisting of radially-disposed fineneedle-shaped spherical aggregates of crystals or spherical masses ofneedleshaped crystals, inasmuch as it will be found that these sphericalcrystals are capable of being more readily washed out or extracted bylixiviation than would be the case if the glucosate were in a differentform. The non-sugar bodies form lead salts which with a properproportion of precipitant are precipitated simultaneously and jointlywith the lead sucrate. The precipitate which is formed consists,therefore, of a mixture of the lead compounds of the non-sugar bodiesand of sucrate. When this mixture suspended in water is treated withcarbonic acid, only the lead sucrate becomes affected, while thecombination of the non-sugars with lead is not affected by the carbonicacid. \Vhen decomposition of the lead compounds of non-sugars occurs, itonly takes place after the lead sucrate has been decomposed. Most ofthese observa tions are entirely novel, and by putting them to practicaluse the improved process which forms the subject of this invention iscarried out somewhat on the following lines:

Oxide of lead or hydrated oxide of lead, or mixtures containing oxide oflead, either hydrated or not and either in a complete or in a nascentform, are triturated with waterand uniformly stirred until they form athin semiliquid mass. Among such mixtures equivalent to oxide of lead,and therefore it to be used as substances therefor, combinations orcompounds of lead-salts with caustic alkalis or alkaline earths may bementioned by way of example. After this trituration stage thesacchariferous solution (such as a solution of molasses, beetroot juice,or the like) which is to be precipitated and which has preferably beenfreed beforehand from such substances as will precipitate under theaction of milk of lime (lime water) or by lead-acetate (neutral orbasic) is added while being kept in a continual state of agitation bystirring. The

stirring should be so vigorous and the concentration ofthesacohariferous juices should be so high that the oxide of lead maynot readily go down to the bottom. Its descent must in fact be uniformin all parts of the mixture, inasmuch as it is most important for thepurposes of sugar extraction and puri fication that there should beformed in as many points as possible centers of crystallization, lestthe proper relation or proportion of the respective atomic weights oflead and sugar should be disturbed While the oxide of lead is collectingat the bottom, for if that precaution were not taken the oxide of leadmight by being covered over with insoluble agglomerations or by becomingitself baked into a lump be withheld from the proper reaction, with theresultthat the precipitation of sugar would be, technically speaking,in-

complete, or the intimate contact of the sacchariferous solution withthe oxide of lead, which is such an indispensable condition for theformation and separation of the saccharate, be effected by passing thesacohariferous liquids through oxide of lead. It is, however, mostimportant that in producing the mixture directly by stirringawell-defined relation should be maintained between the oxide of leadand sugar, inasmuch as if the proportion of lead should be too small thesugar would remain unse'parated, while, on the other hand, too liberalan amount of lead would unduly add to-the difficulty of lixiviation andnecessitate the consumption of too large a quantity of carbonic acid inthe subsequent separation stage. The proper proportion, for example, maybe to every one molecule of cane sugar a little over two molecules ofoxide of lead and to everyone molecule of dextrose or inverted sugar,say, from about one and one-half to two molecules of oxide of leadt'.e., for about three hundred and forty-two parts in weight of cane sugarthere are taken at least four hundred and forty-six parts of oxide oflead, and for one hundred and eighty parts in weight of glucose or themixture of dextrose with levulose called inverted sugar there are takenfrom three hundred and thirty-four to four hundred and forty-six partsof oxide of lead. If instead of the oxide of lead a compound of lead isused, the equivalents of the abovenamed proportions will be employed.While stirring the mixture to make it thorough it should be slowlyheated. Under the joint inliuence of these several factors a chemicalcombination or binding action will in a short time set in, the mixturebeginning to solidify when this pointis about to be reached. Thestirring is then continued until the mixture turns stiff by the formedsucrate, so that the heavy oxide of lead remains in suspension, thoughthe stirring has ceased. In this man ner the oxide of lead not combinedas sucrate may act on the sugar not converted into sucrate and form newamounts of the latter. As

soon as the formation of sucrate has begun 'sugar solution.

the stirring is discontinued, becausethe aggregates of crystals areformed in the best way if the mass reposes.

If it is intended to separate the cane sugar from the glucose, (dextroseand laevulose,) one adds at first the amount of oxide of lead equivalentto the glucose-4'. 8., for one molecule of glucose oneand one-half totwo molecules of oxide of lead or for one hundred and eighty parts inweight of glucose three hundred and thirty-four to four hundred andforty-six parts in weight of oxide of lead. Then the glucosale is formedby stirring and heating the mass. The formed gl ucosate will beseparated mechanically from the solution of sugar, and after standing atrest the solution contains, essentially, cane sugar without any glucose.After the separation of the glucosate the cane sugar will be convertedinto the sucrate by further addition of oxide of lead.

The compound of sugar and leade. 57., a combination of cane sugar andlead, a (30111- bination of glucose and lead, and one of the mixtures ofdextrose and glucose called inverted sugar and lead or the like, or themixtures of these combinationsobtained in the manner above described maybe freed from the parts which have remained in a liquid state or whichare soluble in water by filterin g or otherwise and then washingtheinwith water or submitting them to the dialytic or diffusion process.The liquid separated in the first instance and not yet diluted withwater in the treatment of molasses forms a valuable (becausecomparatively concentrated) solution of salt, with which little or nosugar is mixed; but should it be desired to obtain even these slightadmixtures of sugar, if any, the salt solution need only be treated withfurther quantities of oxide of lead, which will lead to the extractionof the last remnants of sugar just referred to. The sucrate, having beencarefully washed or lixiviated, when it is capable of any amount offurther purification, will dissolve, but with great difficulty. I havefound, indeed, that in the case of compounds of cane sugar and lead therelation is as one to eleven thousand parts of water. This sucrate thenis triturated and treated with carbonicacid or gases containing carbonicacid (the saturation gases) until it is entirely decomposed. There formsan insoluble, mostly basic, carbonate of lead (white lead) and freesugar, the solution of which is separated from the salt of lead byfiltration or the like and then further treated with a view to obtaininga marketable product. The lead is eliminated in toto by this process, sothat not the slightest trace of it will be found in a carefully-filteredBesides, a reliable means of tracing the presence of and expelling anyremnants of lead is afforded by sulphureted hydrogen and thecorresponding sulphur compounds if it should happen that the operationhas not been conducted with sufficient care to eliminate the lead in thefirst instance.

The muddy deposit resulting from saturation, from which the sugar hasbeen extracted, mainly consists of basic carbonate of lead. This is thenintroduced into regenerating-fu rnaces, in which, by being slowlyheated, it is reconverted into oxide of lead. By keeping the air outduring the first heating stage and, if desired, by conducting a currentof steam through the material heated there will only be produced in thefirst instance pure-1'. e., concentrated-carbonic acid, which will return to its proper place in the cycle of opera tions. After expellingthe carbonic acid air may be admitted to the charge under treatmen 1;,the oxygen of which air will assist the regenerating action of the oxideof lead',while the organic admixtures of lead (the non-sacchariferoussubstances) will be entirely burned.

The advantage which the employment of the sugar-extracting process abovedescribed otters over all other existing processes resides in the factthat the carbonic acid contained in the mud collected in the saturationstage may be readily recovered in a high degree of.

concentration, seeing that basic carbonate of lead will decompose attemperatures not exceeding 250 centigrade or thereabout. Thus the heatrequired for highly-concentrated carbonic acid is obtained, whichreturns to its place in the cycle of operations, a result which it hasnot been possible to obtain in any of the extracting processes hithertoknown. Superficial observers might raise this objection to the processherein describedthat in its performance a poisonous substance is madeuse of and that consequently the risk of incompletely separating it fromthe product of daily consumption would always remain attached to it; butthis is a difficulty which the present state of industry enables to bevery readily disposed of,'for it is one of the triumphs of modernscience that it permits the most noxious or dangerous substances to behandied with the greatest ease and with a perfect avoidance of anydanger being involved in the use or consumption of the final product.

Nothing, indeed, is easier than the entire elimination of any lead theremay be still contained in the aqueous solutions. Such lead may, as amatter of fact, be separated with far greater facility than the (alsopoisonous) baryta, which, as is Well known, is an important factor inthe sugar-extracting process known as the baryta saccharificationprocess. Besides, as before stated, sulphureted hydrogen forms anexcellent means for testing the product as to its absolute freedom fromlead-a means which will be as readily available to the manufacturer asto the authorities and, indeed, to the consumers themselves.

I am aware that in the German patent of A. lVohl, No. 85,042, there isdescribed a method of obtaining the sucrate of lead. My presentinvention, however, involves a particular process for manufacturing suchcom pound and the corresponding lead compounds of other sorts of sugar'for instance, glucosein a liquid containing several sorts of sugar.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is vto he performed, I declarethat WhatI claim is- 1. The process of treating saccharine solutions,containing levulose, dextrose and cane sugar which consists in adding alead salt and earth alkali to the solution and agitating it, wherebylead h'ydrate is formed in the mixture,precipitating the levulose anddextrose, removing these precipitates, allowing the remaining solutionto stand until the sucrate crystallizes, and removing the sucrate.

2. The process of treating saccharine solutions, containing levulose,dextrose and cane sugar, which consists in adding a mixture of a leadsalt with an alkali in about the pro portions specified and stirring themixture,

wherehylead oxide is formed in the mixture, precipitating the levuloseand dextrose, removing these precipitates, allowing the remainingsolution to stand until the sucrate crystallizes, and removing thesucrate.

The process of treating saccharine solutions, containing levulose,dextrose and cane sugar which consists in adding a mixture of a leadsalt with an alkaline earth in about the proportions specified andstirring the mixture whereby lead hydrate is formed in the mixture,precipitating the levulose and dextrose, removing these precipitates,allowing the remaining solution to stand until the sucrate crystallizes,and removing the sucrate.

Signed at Cologne, Germany, this 8th day of August, 1895.

GEORG KASSNER. Witnesses:

MARIA NAGEL, Torn WARNER.

